Ignore unrecognised login flows

Update the Login component so that if it sees an unrecognised login flow, it
just ignores it and uses another one, so that riot can still be used with
homeservers supporting custom login types.

src/components/structures/login/Login.js

@@ -76,6 +76,14 @@ module.exports = React.createClass({
 
     componentWillMount: function() {
         this._unmounted = false;
+
+        // map from login step type to a function which will render a control
+        // letting you do that login type
+        this._stepRendererMap = {
+            'm.login.password': this._renderPasswordStep,
+            'm.login.cas': this._renderCasStep,
+        };
+
         this._initLoginLogic();
     },
 
@@ -217,13 +225,29 @@ module.exports = React.createClass({
             loginIncorrect: false,
         });
 
-        loginLogic.getFlows().then(function(flows) {
-            // old behaviour was to always use the first flow without presenting
-            // options. This works in most cases (we don't have a UI for multiple
-            // logins so let's skip that for now).
-            loginLogic.chooseFlow(0);
-            self.setState({
-                currentFlow: self._getCurrentFlowStep(),
+        loginLogic.getFlows().then((flows) => {
+            // look for a flow where we understand all of the steps.
+            for (let i = 0; i < flows.length; i++ ) {
+                if (!this._isSupportedFlow(flows[i])) {
+                    continue;
+                }
+
+                // we just pick the first flow where we support all the
+                // steps. (we don't have a UI for multiple logins so let's skip
+                // that for now).
+                loginLogic.chooseFlow(i);
+                this.setState({
+                    currentFlow: this._getCurrentFlowStep(),
+                });
+                return;
+            }
+            // we got to the end of the list without finding a suitable
+            // flow.
+            this.setState({
+                errorText: _t(
+                    "This homeserver doesn't offer any login flows which are " +
+                        "supported by this client.",
+                ),
             });
         }, function(err) {
             self.setState({
@@ -237,6 +261,16 @@ module.exports = React.createClass({
         }).done();
     },
 
+    _isSupportedFlow: function(flow) {
+        // technically the flow can have multiple steps, but no one does this
+        // for login and loginLogic doesn't support it so we can ignore it.
+        if (!this._stepRendererMap[flow.type]) {
+            console.log("Skipping flow", flow, "due to unsupported login type", flow.type);
+            return false;
+        }
+        return true;
+    },
+
     _getCurrentFlowStep: function() {
         return this._loginLogic ? this._loginLogic.getCurrentFlowStep() : null;
     },
@@ -276,8 +310,20 @@ module.exports = React.createClass({
     },
 
     componentForStep: function(step) {
-        switch (step) {
-            case 'm.login.password':
+        if (!step) {
+            return null;
+        }
+
+        const stepRenderer = this._stepRendererMap[step];
+
+        if (stepRenderer) {
+            return stepRenderer();
+        }
+
+        return null;
+    },
+
+    _renderPasswordStep: function() {
         const PasswordLogin = sdk.getComponent('login.PasswordLogin');
         return (
             <PasswordLogin
@@ -293,21 +339,13 @@ module.exports = React.createClass({
                hsUrl={this.state.enteredHomeserverUrl}
                />
         );
-            case 'm.login.cas':
+    },
+
+    _renderCasStep: function() {
         const CasLogin = sdk.getComponent('login.CasLogin');
         return (
             <CasLogin onSubmit={this.onCasLogin} />
         );
-            default:
-                if (!step) {
-                    return;
-                }
-                return (
-                    <div>
-                    { _t('Sorry, this homeserver is using a login which is not recognised ') }({ step })
-                    </div>
-                );
-        }
     },
 
     _onLanguageChange: function(newLang) {

src/i18n/strings/en_EN.json

@@ -862,7 +862,7 @@
     "Error: Problem communicating with the given homeserver.": "Error: Problem communicating with the given homeserver.",
     "Can't connect to homeserver via HTTP when an HTTPS URL is in your browser bar. Either use HTTPS or <a>enable unsafe scripts</a>.": "Can't connect to homeserver via HTTP when an HTTPS URL is in your browser bar. Either use HTTPS or <a>enable unsafe scripts</a>.",
     "Can't connect to homeserver - please check your connectivity, ensure your <a>homeserver's SSL certificate</a> is trusted, and that a browser extension is not blocking requests.": "Can't connect to homeserver - please check your connectivity, ensure your <a>homeserver's SSL certificate</a> is trusted, and that a browser extension is not blocking requests.",
-    "Sorry, this homeserver is using a login which is not recognised ": "Sorry, this homeserver is using a login which is not recognised ",
+    "This homeserver doesn't offer any login flows which are supported by this client.": "This homeserver doesn't offer any login flows which are supported by this client.",
     "Login as guest": "Login as guest",
     "Return to app": "Return to app",
     "Failed to fetch avatar URL": "Failed to fetch avatar URL",